Mechanical Installation - Grundfos MG serie Montage- Und Betriebsanleitung

6.2.2 Acoustic noise and voltage peaks
Frequency converter operation may cause increased acoustic
noise from the motor and will often expose the motor insulation
system to a heavier load due to voltage peaks reducing motor life.
To prevent the voltage peaks from damaging the motor, make
sure to observe the limits of IEC 60034-17.
Increased acoustic noise and detrimental voltage peaks can be
eliminated by fitting an output filter between the frequency
converter and the motor. For further details, contact your
frequency converter supplier or Grundfos.
Figure 2 shows the maximum permissible voltage peaks
measured at the motor terminals for a specific rise time.
1400
1300
1200
1100
1000
900
800
0.0 0.2 0.4 0.6
Fig. 2 Maximum values for voltage peaks
How to eliminate problems with noise
• Noise-critical applications:
Fit an output filter between the frequency converter and the
motor. This will reduce the voltage peaks and consequently
the noise.
• Particularly noise-critical applications:
Fit a sinusoidal filter. This will reduce the voltage peaks and
optimise the sinusoidal wave of the power supply to the motor.
6.2.3 Cable length
The length of the cable between motor and frequency converter
affects the motor load. Fit a cable that meets the specifications
laid down by the frequency converter supplier.
6.2.4 Speed
Basically, MG motors are not suitable for oversynchronous
operation. Contact Grundfos if oversynchronous operation is
required.
Oversynchronous operation means that the motor runs at a
frequency higher than 60 Hz. This can be achieved by using a
frequency converter.
8
0.8 1.0 1.2 1.4 1.6
t [mS]

7. Mechanical installation

The installation must be carried out by authorised personnel in
accordance with local regulations.
Check by hand that the shaft rotates freely.
7.1 Clearance
To ensure sufficient air circulation, a clearance of minimum 50
mm must be available over/around the motor.
7.2 Terminal box positions
Fig. 3 Permissible terminal box positions
In case of vertically installed motors, the terminal box must not
fall more than 10 ° below the horizontal plane.
Make sure that the motor drain holes are positioned so that
condensed water can escape from the motor.
See section 5.2.1 Number of drain
7.3 Outdoor installation
If it is installed outdoors, protect the motor against water and
sunshine.
7.4 Foundation
Grundfos recommends to install motor and pump on a foundation
which is heavy enough to provide permanent and rigid support.
The foundation must be capable of absorbing any vibration,
normal strain or shock.
Non-compliance may result in functional faults which
Caution
will damage the motor components.
7.5 Alignment
Correct alignment is important to avoid problems with bearings,
vibrations and possible fracture of shaft ends.
7.6 Fitting of coupling parts and pulleys
Fit coupling parts, pulleys and similar components using suitable
equipment and tools that do not damage the motor bearings.
Never knock a coupling part or pulley into position. Always carry
out removal without pressing against the motor.
holes.